Cryoablation versus RF Ablation for AVNRT

A Meta-analysis and Systematic Review

Mikael Hanninen, M.D., F.R.C.P.C.; Nicole Yeung-Lai-Wah, David Massel, M.D., F.R.C.P.C.; Lorne J. Gula, M.Sc., M.D., F.R.C.P.C.; Allan C. Skanes, M.D., F.R.C.P.C.; Raymond Yee, M.D., F.R.C.P.C.; George J. Klein, M.D., F.R.C.P.C.; Jaimie Manlucu, M.D., F.R.C.P.C.; Peter Leong-Sit, M.Sc., M.D., F.R.C.P.C.

Disclosures

J Cardiovasc Electrophysiol. 2013;24(12):1354-1360. 

In This Article

Abstract and Introduction

Abstract

Meta-Analysis of Cryoablation for AVNRT. Introduction: Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common supraventricular tachycardia referred for ablation. High success rates have been accompanied with a small risk of atrioventricular (AV) block. Cryoablation has been used as an alternative to radiofrequency (RF) ablation, but studies have been underpowered in comparing the 2 techniques.

Methods and Results: An electronic search and hand-search of reference lists for published and unpublished data was carried out. Comparative studies (cohort and randomized controlled trials) of RF versus cryoablation for AVNRT were identified independently by 2 reviewers. Searches were limited to English language human studies. The primary metameter was long-term AVNRT recurrence (>2 months postprocedure and ECG/electrophysiology study [EPS]-documented) and secondary metameters included acute procedural failure and AV block requiring pacing. A total of 5,617 patients in 14 trials were included in this systematic review. Acute procedural failure with cryoablation was slightly higher than with RF ablation, but the difference was not statistically significant (risk ratio [RR] 1.44 [95% confidence interval; CI 0.91–2.28], P = 0.12). Long-term recurrence was higher with cryoablation (RR 3.66 [95% CI 1.84–7.28], P = 0.0002) even after adjusting for larger (6 mm) cryocatheter tips, "insurance lesions" and longer (>6 months) follow-up duration. RF ablation for AVNRT was associated with permanent AV block in 0.75% of patients, but was not reported in any patients treated with cryoablation (n = 1066, P = 0.01).

Conclusions: Cryoablation is a safe and effective treatment for AVNRT. Although late-recurrence is more common with cryoablation than with RF ablation, avoidance of permanent AVN block makes it an attractive option in patients where the avoidance of AV block assumes higher priority (such as children and young adults).

Introduction

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common supraventricular tachycardia referred for catheter ablation. Ablation with radiofrequency (RF) energy remains the gold standard for this arrhythmia, but the use of this energy source has been accompanied with a small risk of permanent atrioventricular (AV) block.[1,2] Cryoablation has been used as an alternative to RF ablation and is increasingly being adopted as a first line energy source in children and young adults,[3–5] with a reported rate of acute success ranging from 83% to 98% and an up to 15% chance of tachycardia recurrence at follow-up.[5]

Reported advantages of this technique include a lower risk of AV block in many,[6–9] but not all,[3,4,10–14] published studies. Despite an intrinsically longer lesion application time, some authors have reported comparable procedure times[6–10,12,15] and reduced fluoroscopy times[6,7,9,10,12] due to cryoadhesion (which ensures catheter stability during lesion formation), although others have reported similar or longer fluoroscopy time[3–5,14,16] and longer total procedure time[4,5,11,13,14] with cryoablation. In regards to acute and long-term tachycardia eradication, most series[3,5,6,9,11,13,15,16] favor RF ablation, but others have suggested comparable short- and long-term efficacy.[4,7,8,12] Because published trials to date have been underpowered in comparing efficacy and complications rates between the 2 techniques, we proposed this meta-analysis to better study the differences between these techniques.

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